Gerd Holmström

One-year survival of extremely preterm infants after active perinatal care in sweden

CONTEXT Up-to-date information on infant survival after extremely preterm birth is needed for assessing perinatal care services, clinical guidelines, and parental counseling. OBJECTIVE To determine the 1-year survival in all infants born before 27 gestational weeks in Sweden during 2004-2007. DESIGN, SETTING, AND PATIENTS Population-based prospective observational study of extremely preterm infants (707 live-born and 304 stillbirths) born to 887 mothers in 904 deliveries (102 multiple births) in all obstetric and neonatal units in Sweden from April 1, 2004, to March 31, 2007. MAIN OUTCOME MEASURES Infant survival to 365 days and survival without major neonatal morbidity (intraventricular hemorrhage grade >2, retinopathy of prematurity stage >2, periventricular leukomalacia, necrotizing enterocolitis, severe bronchopulmonary dysplasia). Associations between perinatal interventions and survival. RESULTS The incidence of extreme prematurity was 3.3 per 1000 infants. Overall perinatal mortality was 45% (from 93% at 22 weeks to 24% at 26 weeks), with 30% stillbirths, including 6.5% intrapartum deaths. Of live-born infants, 91% were admitted to neonatal intensive care and 70% survived to 1 year of age (95% confidence interval [CI], 67%-73%). The Kaplan-Meier survival estimates for 22, 23, 24, 25, and 26 weeks were 9.8% (95% CI, 4%-23%), 53% (95% CI, 44%-63%), 67% (95% CI, 59%-75%), 82% (95% CI, 76%-87%), and 85% (95% CI, 81%-90%), respectively. Lower risk of infant death was associated with tocolytic treatment (adjusted for gestational age odds ratio [OR], 0.43; 95% CI, 0.36-0.52), antenatal corticosteroids (OR, 0.44; 95% CI, 0.24-0.81), surfactant treatment within 2 hours after birth (OR, 0.47; 95% CI, 0.32-0.71), and birth at a level III hospital (OR, 0.49; 95% CI, 0.32-0.75). Among 1-year survivors, 45% had no major neonatal morbidity. CONCLUSION During 2004 to 2007, 1-year survival of infants born alive at 22 to 26 weeks of gestation in Sweden was 70% and ranged from 9.8% at 22 weeks to 85% at 26 weeks.

Incidence of and risk factors for neonatal morbidity after active perinatal care : extremely preterm infants study in Sweden (EXPRESS)

Aims:  The aim of this study was to determine the incidence of neonatal morbidity in extremely preterm infants and to identify associated risk factors.

Ophthalmological long term follow up of preterm infants: a population based, prospective study of the refraction and its development

BACKGROUND Numerous studies have reported an increased risk of refractive errors in prematurely born infants, but only few have been long term and strictly population based. METHODS A 3.5 year ophthalmological long term follow up of 248 preterm infants was performed. The infants had been included in a previous epidemiological study of retinopathy of prematurity (ROP) (birth weight ⩽ 1500 grams). The incidence of refractive errors and development of refraction were studied, based on retinoscopies at 6 and 30 months of corrected age. RESULTS The overall incidence ofmyopia was 8% at 6 months, of which 35% was transient, and 10% at 30 months. Of the cryotreated infants, 30–40% were myopic at both retinoscopies. The incidence of astigmatism was 52% at 6 months and 26% at 30 months. Astigmatism was associated with ROP, but not with cryotreated ROP itself. Astigmatism “against the rule” was commoner than astigmatism “with the rule”.Anisometropia occurred in 6.5% of the infants at 6 months and in 8.4% at 30 months. The incidence of anisometropia was higher in eyes with ROP, particularly in cryotreated eyes, which tended to have high and persistent anisometropia. CONCLUSION The risk of refractive errors is higher in preterm infants than in infants born at term, and also prematurely born infants without ROP do run an increased risk of having myopia and anisometropia. We recommend follow up examinations with retinoscopy for all infants included in screening programmes for ROP.

Ophthalmological follow up of preterm infants: a population based, prospective study of visual acuity and strabismus

BACKGROUND/AIMS Prematurely born infants are known to have an increased rate of ophthalmological morbidity. The aim of the present study was to investigate visual acuity and ocular alignment in a population of preterm infants in a geographical area, in infants with and without retinopathy of prematurity (ROP). METHODS A prospective population based study of ophthalmological status of preterm infants with a birth weight of 1500 g or less was performed during 3.5 years, with examinations at 6, 18, 30, and 42 months of corrected age. Visual acuity was tested using linear optotypes. Multiple regression analyses were used to analyse independent risk factors for poor vision and strabismus. RESULTS Poor vision (<0.3) was detected in 2.5% (6/237) of the children. Of these, only two (0.8%) had a severe visual impairment (<0.1). Strabismus occurred in 13.5% (31/229). Children with cryotreated ROP and neurological complications ran the highest risk of poor vision and strabismus, according to multiple regression analysis. Among childrenwithout a history of ROP or neurological complications, 34% had a visual acuity <0.7 and 5.9% had strabismus, compared with 61% and 22%, respectively, among the children with ROP or neurological complications. CONCLUSIONS The overall incidence of subnormal vision and strabismus in children born prematurely was higher than in a full term population of the same age. On the basis of this study, follow up of all preterm infants screened for ROP is recommended and general guidelines are suggested.

Postnatal Head Growth Deficit Among Premature Infants Parallels Retinopathy of Prematurity and Insulin-like Growth Factor-1 Deficit

BACKGROUND. We hypothesized that in premature infants, retinal vascular growth retardation between birth and postmenstrual age of ∼30 to 32 weeks that initiates retinopathy of prematurity is paralleled by brain growth retardation. METHODS. In a prospective longitudinal study, we measured postnatal head growth, retinopathy of prematurity stage, protein and energy intake, severity of illness and serum insulin-like growth factor-1 levels in 58 preterm infants (mean gestational age at birth: 27.6 weeks) from birth until postmenstrual age of ∼40 weeks. RESULTS. Premature infant head growth decelerates dramatically after birth until postmenstrual age of ∼30 weeks. Head growth retardation coincides with retinal vascular growth suppression. Accelerated growth follows between post menstrual ages of ∼30 to 32 weeks and ∼40 weeks. The degree of head growth retardation up to postmenstrual age of 31 weeks corresponds to the degree of retinopathy of prematurity and to the degree of suppression of serum levels of insulin-like growth factor-1. At postmenstrual age of 31 weeks, if a child’s head circumference SD is below −2.5, then the probability of also developing at least stage 3 retinopathy of prematurity increases fivefold compared with head circumference above −2.5 SD (32% vs 6%) suggesting parallel processes in brain and retina. Serum insulin-like growth factor-1 levels correlate positively with head circumference SD score and with the degree of retinopathy of prematurity. CONCLUSIONS. The correlation between head and retinal growth is consistent with insulin growth factor-1 being one of the postnatal growth factors involved in this multifactorial process and also suggests that factors that contribute to retinopathy of prematurity during this critical period may also affect neurological dysfunction. Additional studies are required to establish this connection.

A population based, prospective study of the development of ROP in prematurely born children in the Stockholm area of Sweden.

A prospective population based study including 260 children with a birth weight of 1500 g or less was performed in the Stockholm county. The total incidence of retinopathy of prematurity (ROP) was 40.4%, while severe ROP--that is, stage 3 or more, was seen in 20.0%. Cryotherapy was performed in 10.8%. Logistic regression analysis revealed independent association of both gestational age and birth weight with ROP. The association of gestational age and ROP was significantly stronger, indicating that the degree of immaturity of the eye is a main predictive factor for the development of ROP. The purpose of a general screening for ROP is to identify children requiring cryotherapy. Based on these results it seems appropriate to include children with a gestational age of 32 weeks or less in such a programme and a first examination at 5-6 weeks of postnatal age is suggested.

Incidence of ROP in two consecutive Swedish population based studies.

Aims: To prospectively analyse the present incidence of ROP (retinopathy of prematurity) in a well defined geographical area in Sweden, and to compare it with that from a decade earlier in exactly the same area. Methods: Infants born between 1 August 1998 and 31 July 2000 with a birth weight of 1500 g or less were studied. They were screened for ROP from 5 weeks of postnatal age until the retina was entirely vascularised. The incidence of ROP, with its various stages, was compared with that of a previous (1988–90) population based study in the same geographical area. Results: The incidence of ROP in the present study was 36.4% (mild (18.2%) and severe ROP (18.2%)), which was similar to that of the previous study. Gestational age at birth remained the most important risk factor for ROP. We found a change in the distribution of ROP. The probability of ROP, particularly severe ROP, was highest in the most immature infants while it was lower in the least immature ones. Conclusions: The incidence of ROP remained the same in two consecutive population based studies. The more “mature” infants developed ROP, particularly severe ROP, less often, while the most immature infants had ROP more often, particularly severe ROP.

Regressed retinopathy of prematurity and its sequelae in children aged 5-10 years.

Regressed retinopathy of prematurity (ROP) and its sequelae were studied in children born prematurely (less than 1501 g birth weight and/or less than 33 weeks gestational age) in Stockholm county during 1976-81. Through various searches of the records at the different eye departments and other sources in Stockholm county we found that 134 out of a total of 528 premature babies (25.4%) had needed ophthalmic care for different reasons. They were re-examined and reliable information on the fundus could be obtained for 105 of them. The frequency of regressed ROP was 45.5%. Severe forms with vitreoretinal scarring and retinal traction were seen in 9.7% of cases and moderate forms with pigmentary changes and/or vitreoretinal interphase changes in 35.8%. The sequelae of regressed ROP were mainly reduction of visual acuity and myopia. Children with a birth weight below 1000 g and a gestational age less than 30 weeks presented the highest rate of regressed ROP (68.5% and 61.9%) and ocular abnormalities.

Screening for retinopathy of prematurity: evaluation and modification of guidelines

Aims: To evaluate current screening guidelines for ROP (retinopathy of prematurity) and to determine whether they can be modified. Methods: In accordance with the authors’ present criterion, infants born in Stockholm County, Sweden, from 1 August 1998 to 31 July 2000, with a gestational age of ≤32 weeks, were screened for ROP. The effectiveness of screening was studied. Results: The incidence of ROP was 25.5% in this study. A dropout group comprising almost 20% of the population studied (≤32 weeks), was never referred, were lost to follow up, or died before screening was completed. No infant with a gestational age of >31 weeks at birth developed severe ROP (stages 3–5) and no infant with a gestational age of >29 weeks was treated for ROP. Conclusion: 80% of infants in this population with a gestational age at birth of ≤32 weeks, the current screening criterion, were effectively screened for ROP. The authors recommend that the screening criterion be lowered to ≤31 weeks since no infant with severe ROP would have been missed.

Contrast sensitivity in 10 year old preterm and full term children: a population based study.

Aims: To determine the contrast sensitivity (CS) in 10 year old prematurely born children, previously included in a population based study on the incidence of retinopathy of prematurity (ROP), and in full term controls. Methods: This study included 205 prematurely born children and 215 children born at term, from the same geographical area and study period. CS was assessed monocularly with the Vistech 6500 test at five spatial frequencies (1.5–18 cycles/deg). Results: Prematurely born children had statistically significant lower CS at all frequencies, compared to full term ones. The mean differences in logarithmic CS were 0.03 (1.5 cycles/deg), 0.09 (3 cycles/deg), 0.10 (6 cycles/deg), 0.12 (12 cycles/deg), and 0.19 (18 cycles/deg). Even when the children with ROP and neurological disorders were excluded there was a difference between the two groups. Children who had been treated with cryotherapy had the lowest CS. Conclusion: CS was lower in 10 year old prematurely born children than in full term ones of the same age. Whether this finding affects their visual function in daily life is uncertain.